1. Field of the Invention
The invention relates generally to an apparatus for inserting fixing elements into a work piece.
2. Description of Background Art
Conventional devices for inserting a fixing element into a work piece typically include a nose piece with fixing elements held under a lower end of a drive rod penetrating through the nose piece. One approach for holding the fixing elements 100 in position under the nose piece 450 involves equipping the device with one or more spring-loaded fingers 459 with portions that extend under the outer portions 110o of the flange 110 of the fixing element 100. Portions of the fingers 459 extending under the outer portions 110o of the flange 110 hold the fixing element 100 in position under the drive rod 20. In addition to spring-loaded fingers 459, a magnet may be provided in the nose piece to hold the fixing element in position below the drive rod. In devices equipped with spring loaded fingers. When the drive rod moves downwardly and reaches the upper surface of the fixing element, the fingers holding the fixing element are forced open by the impact of the drive rod on the fixing element.
FIG. 16 is a perspective view of device with a conventional nose piece 450 with angled fingers 459 that do not open prior to driving the fixing element 100 into the work piece. FIG. 17 is a cut-away view of the conventional device of FIG. 16, having a nose piece 450 with angled fingers 459 that do not open prior to driving the fixing element 100 into the work piece. FIG. 18 is another perspective view of the conventional device of FIG. 16, having a nose piece 450 with angled fingers that do not open prior to driving the fixing element 100 into the work piece.
Conventional devices have employed spring-loaded fingers extending horizontally under the flanges, and also spring-loaded fingers 459 (such as those shown in FIGS. 16-18) that are angled at approximately 45°. While fingers angled at 45° reduce the force on the flanges, compared to fingers extending horizontally, flange distortion and spring breakage remain a problem. Moreover, spring-loaded fingers 459 that are angled at approximately 45° fail to provide sufficient guidance when the fixing element 100 is transferred from a feed track 60 to the position under the nose piece 450.
As speed of the drive rod 20 increases, the speed of opening of the fingers 459 leads to frequent spring breakage. As the speed of the drive rod 20 increases still further, the at least outer portions of the flange of the fixing element 100 are not able to withstand the very rapid application of force to open the fingers 459, and the flange 110 is often bent and distorted during insertion.
To make a lightweight portable device or hand tool (or standalone machine) for inserting fixing elements, the speed of the drive rod must be very fast in order provide enough force to drive the fixing element into the work piece. At high speeds, the problems described above make the conventional finger arrangement unworkable.